Typical building fire alarm systems include a number of detectors positioned throughout a building. Signals from those detectors are monitored by a fire panel which, upon sensing an alarm condition, activates a number of notification appliances throughout the building. The notification appliances can include audible alarms, such as sounders or horns, and visual alarms, which can include flashing light strobes. Typically, the fire panel drives these devices over one or more “notification appliance circuits” (NACs).
In very large buildings, a plurality of individual fire panels may be used to service the building. For example, each floor of such a building may be serviced by its own fire panel, with all of the fire panels connected to a network. In addition, for commercial and/or educational campuses, certain portions of the campus may be served by different fire panels. For example, a courtyard or atrium that adjoins several buildings or building floors may be serviced by a plurality of notification appliances (i.e., strobes) controlled by different fire panels.
Such installations may require that the output of all notification devices be synchronized. For example, where multiple strobes are used, the strobe flashes must be synchronized to reduce the risk of seizure for people having photosensitive epilepsy. Underwriters Laboratories (UL) can require such strobes to be controlled to ensure that an individual viewing multiple strobes will see effective flash rates no higher than a predetermined amount to reduce the aforementioned risk. As can be appreciated, this presents a problem where the multiple flashing strobes are controlled by different fire panels. To date, the only solutions to this problem have been hardware based. For example, to synchronize the strobes within a large area, all of the strobes would need to be run from a single fire panel, which undesirably requires wiring all of the affected areas back to the single fire panel rather than wiring the strobes to the closest for panel. As can be appreciated, hardware synchronization increases system costs in terms of additional time.
Thus, there is a need for an improved system and method for synchronizing the flashes of a plurality of strobe lights controlled by a plurality of different fire panels. The system and method should be appropriate for use across a variety of modern distributed network systems used to link multiple fire panels.